This invention relates to a light-sensitive silver halide color photographic material. More particularly, the present invention relates to a light-sensitive silver halide color photographic material which is high in sensitivity and can also exhibit excellent graininess.
Heretofore, it has been desired to develop a light-sensitive silver halide color photographic material (hereinafter abbreviated as "light-sensitive material") which is high in sensitivity and excellent in image quality. Particularly, in recent years, as the increase of chances of photographing under bad conditions with small quantity of light such as indoors and also with the progress of small formatting of light-sensitive materials, it has been strongly desired to develop a light-sensitive material which is high in sensitivity and excellent in image quality such as sharpness, graininess and interimage effect.
However, it is difficult to effect both higher sensitization and improvement of image quality.
For example, as the layer constitution for higher sensitization, the following consistution has been known. That is, in a layer constitution of regular sequence having respective layers of red-sensitive, green-sensitive and blue-sensitive light-sensitive silver halide emulsion layers (light-sensitive silver halide emulsion layer is hereinafter referred to merely as "emulsion layer") provided by coating on a support, a part or whole of the light-sensitive emulsion layers are separated into a high sensitivity silver halide emulsion layer (hereinafter referred to as high sensitivity emulsion layer) and a low sensitivity silver halide emulsion layer (hereinafter referred to as low sensitivity emulsion layer), each containing a diffusion resistant coupler capable of color forming to substantially the same hue, and these layers are laminated adjacent to each other.
According to such a constitution, there is the problem that the emulsion layer on the side nearer to the support will suffer from decreased dosage of light on exposure of light because of absorption by other emulsion layers positioned on the side farther from the support. Moreover, during development, a considerably long time is required for diffusion of a developer.
Thus, according to such a layer constitution of regular sequence, due to loss in dosage of exposure and retardation in development, it is difficult to achieve higher sensitization in green-sensitive and red-sensitive emulsion layers positioned as lower layers (nearer to the support side).
On the other hand, techniques to alter the order of respective emulsion layers laminated are known.
For example, U.S. Pat. No. 3,663,228 discloses a constitution comprising:
(a) the respective low sensitivity emulsion layers of red-sensitive, green-sensitive and blue-sensitive layers provided by coating on a support in the order mentioned from the support side; and
(b) the respective high sensitivity emulsion layers of red-sensitive, green-sensitive and blue-sensitive layers provided by coating on the side farther from the support in the order mentioned from the support side.
This technique can afford higher sensitivity as compared with the constitution of regular sequence as described above. However, as can clearly be seen from the fact that each unit of laminates of the aforesaid high sensitivity emulsion layer and low sensitivity emulsion layer are separated by ND (neutral density) filter, higher sensitization is not to the fore of interest at all.
Next, U.S. Pat. No. 3,658,536 discloses a technique to cancel loss of dosage in a green-sensitive emulsion layer having great effect on visual sensitivity by positioning the green-sensitive emulsion layer on the surface side farther from the support.
However, according to such a layer constitution, high sensitization technique of a blue-sensitive emulsion layer is not dealt with at all, and also improvement of sharpness graininess and interimage effect is not satisfactory.
Otherwise, there have also been known techniques concerning alteration of the layer constitution as disclosed in Japanese Unexamined Patent Publications Nos. 49027/1976 and 97424/1978 and U.S. Pat. No. 4,129,446.
However, any of these techniques, while higher in sensitivity than the layer constitution of regular sequence as described above, is not only unsatisfactory in sensitivity of green-sensitive and red-sensitive emulsion layers but also unsatisfactory in effects of improvement of image quality such as graininess and sharpness.